Lambright (2010) addresses an important weakness of the expectancy theory: it makes no distinction between certainty and uncertainty conditions. Indeed, the expectancy theory does not take into account the cases in which there is uncertainty of the outcome. Since expectancy model outcomes do not have to be the same in certain outcome cases compared to cases in which outcomes are uncertain, Lambright suggests a distinction between these circumstances should be included in the formula.
Therefore the author suggest an extended version of the expectancy theory, in which the level of certainty is included:Motivation = Expectancy × Instrumentality × Valence × Certainty.
In this formula, the certainty level has a value from zero to one, in which zero means there is no certainty at all and one means there is full certainty of outcomes. As a result, for highly certain cases this formula would act the same way as the traditional expectancy theory formula. For lower certainty-levels, motivation will be lower than the traditional formula.
Lambright, K. T. (2010). An Update of a Classic: Applying Expectancy Theory to Understand Contracted Provider Motivation. Administration & Society, Sage Publications.

People Can Look Aroundvrooland, consultant, NetherlandsSo you can add Ajzen's theory to it. Are there any social norms among important other people? Any ideas or criteria?